The present invention relates to apparatus and devices for detecting contraband, and more particularly to a hand-held contraband detector designed to detect contraband, such as drugs, hidden behind panels or inside of an enclosure within a few inches of the hand-held device.
Law enforcement agencies, including customs officials, charged with searching persons and property for concealed contraband, face an ever increasing and more difficult challenge as increased amounts of illegal contraband are transported from one location to another, particularly where such contraband is hidden or concealed with increased ingenuity while in transit. Hence, there is an increased need for reliable, easy-to-use, contraband detectors to assist such law enforcement agencies as they perform their never-ending vigil to detect illegal drug traffic.
It is known in the art to provide a hand-held contraband detector device that includes a single source of low energy gamma rays. In use, the hand-held device is scanned over an area being searched, i.e., over a target volume (an object being investigated), so that the low energy gamma rays are directed into the target volume. Depending upon the composition of the target volume, a portion of the gamma rays are backscattered and returned to the hand-held device. By quantitatively sensing these backscattered gamma rays, a rough qualitative determination can be made as to the density composition of the target volume. From such density information, reasonable inferences may be drawn as to whether the target volume includes certain types of contraband material. If contraband is sensed, an indicator on the sensor changes sufficiently to alert the searcher that contraband may be present. In this way, the hand-held detector greatly aids the searcher in locating concealed contraband.
Despite the advantages provided to the searcher with such prior hand-held detectors, the use of such detectors has also created some problems. For example, prior detectors of this type have frequently used americium 241 as the single source of low energy gamma rays. Unfortunately, the energy of the gamma rays available from americium 241, approximately 60 KeV, is not sufficient to allow the gamma rays to readily penetrate some common materials wherein contraband may be hidden, although it is well suited for detecting contraband in other common materials. Thus, the searcher, while readily detecting contraband in some materials using such device, does not detect identical contraband in other materials. Hence, much contraband is not detected using such prior devices.
Further, many prior hand-held detectors have been housed in a pistol-shaped housing in an attempt to make such detectors easier to handle and use. Unfortunately, this configuration has proven to be somewhat threatening for most searchers and searchees as the detector has the rough appearance of a firearm that the searcher is pointing at the searchee or the searchee's property.
One type of prior hand-held detector uses barium 133 as the single source of rays. Advantageously, barium 133 provides gamma rays having more energy (approximately 350 KeV) than the gamma rays from americium 241, thus allowing the gamma rays to more readily penetrate the different types of materials in which contraband may be concealed. However, in order to properly shield the increased energy gamma ray source, such unit includes a structure that is much heavier than the device using americium 241. Further, in order to release the gamma rays from the device, the user must continually hold down a spring-loaded trigger handle. Use of this device may thus become very tiring as the user must both lift a heavier device and continually depress the spring-loaded trigger.
Another problem associated with prior hand-held contraband detectors relates to the manner in which the device signals that contraband has been detected. Prior devices typically include an indicator, either a digital or analog readout device, that provides a visual indication to the user of the amount of backscattered gamma rays received, and hence an indication of the composition of the target volume. Unfortunately, this indicator is integrally included as part of the hand-held detector. Hence, in scanning hard-to-reach locations, such as under a table or inside of the fender well of a motor vehicle, the user must frequently place himself or herself in difficult positions in order to be able to place the detector in the desired location while still being able to see the indicator on the detector.
In view of the foregoing, it is evident that what is needed is a light-weight hand-held contraband detection device that is ergonomically easily to use, is not threatening to either the searcher or the searchee, and produces reliable, consistent results regardless of the materials in which the contraband may be hidden. The present invention advantageously addresses these and other needs.